Rotary pilot protractor



Aug. 27, 1957 J. c. BAKER ROTARY PILOT PROTRACTOR Fueq A ril 9, 1954 2 Sheets-Sheet 1 INVENTOR.

1957 J. c. BAKER 2,803,881

ROTARY PILOT PROTRACTOR Filed April 9, 1954 2 Sheets-Sheet 2 IN VEN TOR.

JOSEP/l c. BAKEA:

United States Patent ROTARY PILOT PROTRACTOR Joseph C. Baker, Prospect Park, Pa. Application April 9, 1954, Serial No. 422,112

4 Claims. (CI. 33-75).

This invention relates to geometrical instruments and more particularly to a protractor of the type for use of tool and die makers as a scribing instrument.

It is an object of this invention to provide a protractor for use in conjunction with a pilot hole in any fixture, jig, tool, etc. where any number of holes, key slots, or grooves that need to be laid out for drilling, machining, inspection, etc. can be done in far less time than with prior instruments of this type.

It is a further object of this invention to provide a rotary pilot protractor in which layout or inspection is considerably speeded and made more rapid by use of a double-end straight edge.

It is a further object of this invention to provide a rotary pilot protractor which is accurate in its operation, simple in construction, capable of rugged extended use over long periods of working time without necessary readjustment, and which may be accurately set at any given reading.

Yet another object of this invention is to provide a rotary pilot protractor which when once set in a desired position of adjustment will leave both hands of the operafor free for subsequent scribing operations in the layout of the work to be accomplished.

Other objects and advantages will become apparent from the following detailed description, forming the specification, and taken in conjunction with the accompanying drawings, wherein:

Figure l is a top plan view of a protractor embodying this invention;

Figure 2 is a side elevational view thereof;

Figure 3 is a vertical cross sectional view taken on line 3-3 of Figure 1;

Figure 4 is a horizontal cross sectional view taken on a greatly enlarged scale, taken on line 44 of Figure 3, and shown fragmentarily; and

Figure 5 is an exploded view of the central portion of the protractor indicating the relation of the elements on the central shaft thereof.

With continued reference to the drawings, there is shown the protractor of this invention, generally indicated at and which comprises an upstanding shaft, generally indicated at 12 having the lower end 14 thereof provided with spaced longitudinal slots 16 extending through the lower edge of the shaft and in communication with the central longitudinal bore 18 through the shaft, the lower end 14 being adapted to be received in a pilot hole of a workpiece (not shown) upon which work is to be laid out, to define an anchoring means.

The shaft 12 has at its upper end 20 external screw threads 22 and is formed intermediate its upper and lower ends with an annular flange 24 having an undercut portion 26 defining a second flange of lesser diameter, and between the screw threads 22 and the annular flange 26 of smaller diameter there is provided an outwardly extending key 28. j

A straight edge 30 of elongated, generally rectangular shape and of flat bar material is provided with parallel opposite side edges 32 and 34 extending longitudinally thereof to define the edges along which straight lines may be scribed using these edges as guides, and further provided with a central circular scale plate 48 having a central opening therethrough to receive the annular flange 26 therein and provided with an annular recess 36 concentric with the opening centrally therethrough to receive therein the annular flange 24 with the annular flange 24 having its lower surface coplanar with the lower or bottom surface of the straight edge or protractor 3% so that the smooth, continuous surface is pro vided on the bottom of the straight edge or protractor, and this lower surface 36 is adapted to overlie the workpiece in which the lower end 14 of the shaft 12 is received in a pilot hole therein so that the lower face or surface 36 is in face to face relation with. the workpiece.

The straight edge or protractor 30 is thus carried by the shaft 12 intermediate its ends for movement in an arcuate path perpendicular to the shaft and adapted to overlie a workpiece in face to face relation thereto.

As clearly shown in Figure 3, the annular flange 26 is of considerably greater width than the flange 24 and extends beyond the top surface of the straight edge or protractor St) to receive thereon the central opening through a gear 38 so that the gear 38 is in overlying relation to the straight edge or protractor 30 and in face to face relation thereto and fixed thereto by a plurality of small dial pins 39. The gear 38 is rotatable on the flange 26 of the shaft 12 so as to cause rotation of the protractor 30.

A spring washer 4a is carried by the shaft 12. The spring washer 40 is of concavo-convex formation and has its concave side extending toward the flange 26 and the gear 33 so that the circumferential edge of the Washer is in contact with the gear 38.

A protractor body 42 which forms a vernier plate or ring is of generally a truncated cone formation having a beveled peripheral side wall 44 on which is inscribed an arcuate vernier scale 46 adapted to register with the circular scale plate 48 on the protractor 30 between the arms 49 and 50. The scale is marked off in major increments of thirty degrees with the scale being repetitious consecutively in increments of thirty degrees after each ninety degrees of the three hundred and sixty degrees of the circle has been marked off. As will be readily appreciated, the circular scale plate 48 is formed integrally with the protractor or straight edge 39 and disposed centrally intermediate its ends so that the arms 49 and 50 extend equidistantly from either side of the circular scale plate 48 and perpendicularly to the center line of the shaft 12 with the straight edge 34 being disposed along the diameter of the circular scale plate 48. A central opening is provided transversely through the vernier ring 42 so as to be received on the shaft 12 and this opening 52 has an enlarged annular recess 54 concentric therewith to provide a space wherein the gear 38 and spring washer 40 may be received as the side wall 44 of the ring 42 overlies the top surface of the circular scale plate 48, but can be moved longitudinally of the shaft to thereby permit the circular scale 48 to have its markings register with the scale 46 formed on the tapered circular side wall 44 of the plate. Also, the wall 56 of the recess 54 remote from the end of the recess which opens to the lower end of the vernier ring 42 is in engagement with the convex side of the spring washer 40.

The protractor body or vernier ring 42 is operatively connected to the shaft 12 by the key 28 which extends into a keyway 58 formed in the protractor body 42. Hence, the protractor body is carried by the shaft 12 3 against rotation thereabout and overlies the protractor circular scale plate 48.

To secure the protractor 30 in a selected position in its arcuate path of movement with respect to the ring 42, a lock nutr60 is th'readingly carried on the threaded upper end portion of the shaft 12 so that it will contact the upper surface of the Vernier ring 42 and when tightened thereagainst will cause the plate 48 to move longitudinally of the shaft toward the plate 42 and resiliently urge the spring washer 40 against the gear 38 to lock the gear against rotation. This will prevent further movement .of the protractor since the gear 38 will frictionally be engaged at the upper surface of the plate 48 so as to be locked and lock the protractor in a selected position.

The gear 38 is one element of the means whereby the protractor 30 may be moved in its arcuate path. The other element of the means to move the protractor 30 in its arcuate path is the Vernier gear 62 which is in mesh with the gear 38 and is carried at the lower end of a line of the shaft 64 and preferably formed integrally therewith by the stem 70. By rotating the Vernier knob 68, the gear 62 will impart rotation to the gear 38 which in turn will cause the protractor 30 to move in its arcuate path about the shaft as a vertical axis.

An expansion bolt 72 has one end 74 thereof externally threaded remote from the tapered conical head 76 which carries thereon and extending outwardly therefrom the guide pin 78. The shank 80 of the expansion bolt extends through the bore 18 of the shaft 12 with the externally threaded end 74 extending beyond the upper end of the shaft and the guide pin 78 received in one of the slots 16 in the lower end 14 of the shaft so that the head 76 is in engagement with the outwardly tapering extending beyond the upper end of the shaft 12 and may be tightened thereon so as to engage the upper end surface of the shaft and when tightened thereon will draw the expansion bolt within the bore 18 and cause the lower slotted end 14 of the shaft 12 to expand against the side Walls of the pilot hole in which it is placed on the workpiece to define an anchor whereby the anchoring means 14 of the shaft can be expanded and secured in such pilot hole. This leaves the hands of the operator free for subsequent laying out and scribing operations in connection with the workpiece upon which the protractor device 10 has been mounted.

With the lower end 14 of the shaft 12 tightened in the pilot hole of the workpiece, and the lock nut 60 tightened down against the top of the Vernier ring 42 to move the ring toward the plate 48 so as to cause the spring Washer to lock the protractor or straight edge 30 in a selected position, the lock nut 60 may then be backed off so as to permit movement of the straight edge or protractor 30 in its arcuate path. It is contemplated that the zero setting or marking on the arcuate scale 46 of the Vernier ring 42 will be in register with a zero mark on the protractor circular scale plate 48 and in line With the center line of a workpiece. With the lock nut 60 loosened, the straight edge or protractor can be moved to any desired setting in degrees and minutes over the entire three hundred and sixty degrees of the circle without danger of error in use due to the similar readings which would be obtained on diametrically opposite sides of the scale 48 with reference to the guide edge 34. As the desired setting is obtained, the lock nut 60 is then tightened to secure the straight edge or protractor 30 in this selected position in its path of movement.

Since the lower end of the shaft 12 will be tightened by the lock means, lock nut 84, carried by the bolt 72 4 to be anchored in the pilot hole of the workpiece, both hands of the operator will be free as contrasted to the ordinary type of protractor where one hand of the operator is required to hold the protractor device against a make-shift straight edge or scale after locating the exact center line of the job and making sure that the scale and protractor square is on the exact center where the center line comes tangent thereto and then must use a scribe to mark the desired line. With the present protractor device, it is merely necessary to get the easily read desired setting in degrees and minutes, lock the setting by the lock nut which defines means carried by the shaft for moving the ring 42 longitudinally of the shaft 12 and toward the plate 48 against the inherent resilience of the washer 40 for locking the protractor or straight edge in a desired position in its path of movement, and scribing the desired line along the selected angle.

From the foregoing, it will beapparent that there has been provided a rotary pilot protractor which comprises an upstanding shaft 12 having the lower end 14 provided with spaced longitudinal slots defining the anchoring means to be received in a pilot hole of a workpiece, a straight edge or protractor 30 carried by the shaft 12 for movement in an arcuate path perpendicular to the shaft and disposed intermediate the ends of the shaft, the straight edge 30 adapted to overlie the workpiece, a protractor body or Vernier ring 42 carried by the shaft 12 against rotation thereabout and movable longitudinally thereof toward and away from and in overlying relation to the plate 42 of the straight edge 30, the shaft 12 being provided with a central bore 18 longitudinally therethrough to receive therein an expansion bolt 72 extending therethrough, lock nut 84 carried by the bolt to tighten the anchoring means of the shaft 12 in the pilot hole, means in the form of the gear 38 and Vernier gear 62 for rotating the straight edge in its arcuate path, and lock means 60 carried by the shaft 12 for securing the straight edge in a selected position in its arcuate path of movement by causing the ring to move longitudinally of the shaft toward the plate 48 and against the resilience of the washer 40.

It will be appreciated that the Vernier arrangement will be used to get an exact reading in minutes and fractions thereof after the straight edge has been rotated to the approximate reading.

While there are shown and described the preferred embodiment of the invention, it is to be understood that the structure is susceptible to change and modification within the practicability of the invenion and therefore should be limited only by the scope of the claims appended hereto.

What is claimed is:

1. A rotary pilot protractor for use on a workpiece having a pilot hole therein, comprising an upstanding shaft having a central bore longitudinally therethrough and provided at its lower end with expandable means for anchoring said shaft in the pilot hole, a protractor straight edge having a central plate, said plate carried on said shaft for movement of said straight edge in an arcuate path about the axis of said shaft in overlying relation to the workpiece, a protractor ring carried by said shaft against rotation relative thereto and for movement longitudinally thereof in overlying relation tosaid plate, means carried in said shaft bore for expanding said means at the lower end of the shaft to anchor the shaft in the pilot hole, resilient means carried by said shaft interposed between said ring and said plate and movable into locking relation with said plate upon movement of said ring toward said plate to secure said straight edge in a selected position in its arcuate path of movement, and means carried by said shaft for moving said ring longitudinally of said shaft.

2. A rotary pilot protractor for use on a workpiece having a pilot hole therein, comprising an upstanding shaft having a central bore longitudinally therethrough asoassr and provided at its lower end with expandable means for anchoring said shaft in the pilot hole, a protractor straight edge having a central plate, said plate carried on said shaft for movement of said straight edge in an arcuate path about the axis of said shaft in overlying relation to the workpiece, a protractor ring carried by said shaft against rotation realtive thereto and for movement longitudinally thereof in overlying relation to said plate, means carried in said shaft bore for expanding said means at the lower end of the shaft to anchor the shaft in the pilot hole, resilient means carried by said shaft interposed between said ring and said plate and movable into locking relation with said plate upon movement of said ring toward said plate to secure said straight edge in a selected position in its arcuate path of movement, and means carried by said shaft for moving said ring longitudinally of said shaft, means for moving said straight edge comprising a gear rotatably mounted on said shaft and se cured upon said plate, a gear carried by said ring and rotatable about an axis parallel to the axis of said shaft and in mesh with said first-mentioned gear to impart rotation thereto for moving said straight edge in its arcuate path.

3. A rotary pilot protractor for use on a workpiece having a pilot hole therein, comprising an upstanding shaft having a central bore longitudinally therethrough and provided at its lower end with expandable means for anchoring said shaft in the pilot hole, a protractor straight edge having a central plate, said plate carried on said shaft for movement of said straight edge in an arcuate path about the axis of said shaft in overlying relation to the workpiece, a protractor ring carried by said shaft against rotation relative thereto and for movement longitudinally thereof in overlying relation to said plate, means carried in said shaft bore for expanding said means at the lower end of the shaft to anchor the shaft in the pilot hole, resilient means carried by said shaft interposed between said ring and said plate and movable into locking relation with said plate upon movement of said ring toward said plate to secure said straight edge in a selected position in its arcuate path of movement, and means carried by said shaft for moving said ring longitudinally of said shaft, said expandable means having longitudinally extending, angularly spaced slots opening into said bore and through the lower edge of said shaft to define a slotted lower end, said means for expanding the slotted lower end of said shaft including an expansion bolt disposed within said bore with its head disposed within said lower end and a portion of its shank extending outwardly from the upper edge of said shaft, and a nut carried by said bolt on its outwardly extending shank portion bearing against the upper end of said shaft to draw the bolt head into said slotted lower end and causing it to expand.

4. A rotary pilot protractor for use on a workpiece having a pilot hole therein, comprising an upstanding shaft having a central bore longitudinally therethrough and provided at its lower end with expandable means for anchoring said shaft in the pilot hole, a protractor straight edge having a central plate, said plate carried on said shaft for movement of said straight edge in an arcuate path about the axis of said shaft in overlying relation to the workpiece, a protractor ring carried by said shaft against rotation relative thereto and for movement longitudinally thereof in overlying relation to said plate, means carried in said shaft bore for expanding said means at the lower end of the shaft to anchor the shaft in the pilot hole, resilient means carried by said shaft interposed between said ring and said plate and movable into locking relation with said plate upon movement of said ring toward said plate to secure said straight edge in a selected position in its arcuate path of movement, and means carried by said shaft for moving said ring longitudinally of said shaft, means for moving said straight edge comprising a gear rotatably mounted on said shaft and secured upon said plate, a gear carried by said ring and rotatable about an axis parallel to the axis of said shaft and. in mesh with said first-mentioned gear to impart rotation thereto for moving said straight edge in its arcuate path, said expandable means having longitudinally extending angularly spaced slots opening into said bore and through the lower edge of said shaft to define a slotted lower end, said means for expanding the slotted lower end of said shaft including an expansion bolt disposed within said bore with its head disposed within said lower end and a portion of its shank extending outwardly from the upper edge of said shaft, and a nut carried by said bolt on its outwardly extending shank portion bearing against the upper end of said shaft to draw the bolt head into said shaft to draw the bolt head into said slotted lower end and causing it to expand.

References Cited in the file of this patent UNITED STATES PATENTS 699,245 Russell May 6, 1902 1,314,184 Clark Aug. 26, 1919 2,124,358 Vancura July 19, 1938 FOREIGN PATENTS 290,017 Italy Nov. 5, 1931 113,058 Sweden Ian. 30, 1945 

